Switch to lodash for memory lookup

screeps-game-api/src/memory.rs

@@ -1,8 +1,62 @@
-use std::fmt;
+//! Interface with Screeps' `Memory` global variable
+//! 
+//! Screeps' memory lives in the javascript `Memory` global variable and is 
+//! encoded as a javascript object. This object's reference is tracked within 
+//! rust as a `MemoryReference`. The [`root`] function gives access to a 
+//! reference to the `Memory` global object.
+//! 
+//! # Typing
+//! Contrary to accessing the memory in javascript, rust's strong type system, 
+//! requires that read values be assigned a type. To facilitate this, the
+//! `MemoryReference` provides methods to read a part of the memory as a
+//! certain type. If the value read cannot be transformed to the requested
+//! type, the method return `None`.
+//! 
+//! # Accessing the memory
+//! Memory can be accessed in two ways: 
+//!  - via _keys_
+//!  - via _paths_ (methods prefixed with `path_`)
+//! 
+//! In both cases, if the value requested is `undefined`, `null`, or even just
+//! of the wrong type, the method returns `None`.
+//! 
+//! ## Accessing memory with a _key_
+//! Since a `MemoryReference` represents a javascript object, its children can
+//! be accessed using the `object["key"]` javascript syntax using type methods.
+//! ```no_run
+//! let mem = screeps::memory::root();
+//! let cpu_used_last_tick = mem.int("cpu_used_last_tick").unwrap();
+//! ```
+//!  
+//! ## Accessing memory with a _path_
+//! A quality of life improvement upon the key access is through full path. In
+//! javascript, it is possible to query a value with a full path: 
+//! ```javascript
+//! var creep_time = Memory.creeps.John.time;
+//! ```
+//! 
+//! To emulate this behavior in rust, you can write such a path to a string and
+//! it will fetch the javascript object using 
+//! [lodash](https://lodash.com/docs/4.17.10#get) and convert the result
+//! depending on the method used. For example,
+//! ```no_run
+//! let mem = screeps::memory::root();
+//! let creep_time = mem.path_num("creeps.John.time").unwrap();
+//! ```
+//! 
+//! # Other methods that provide `MemoryReference`s
+//! In addition to accessing the memory from the root, it is possible to
+//! access the memory via creeps, spawns, rooms and flags. Accessing the memory
+//! from those objects will also result in a `MemoryReference` which instead
+//! points at the root of this object's memory.
+//! 
 
+use std::fmt;
 use stdweb::unstable::{TryFrom, TryInto};
 use stdweb::{Array, JsSerialize, Reference, Value};
 
+use ConversionError;
+
 #[derive(Clone, Debug)]
 pub struct UnexpectedTypeError;
 
@@ -13,7 +67,8 @@ impl fmt::Display for UnexpectedTypeError {
     }
 }
 
-/// TODO: do we even need this over just a raw 'Reference'?
+// TODO: do we even need this over just a raw 'Reference'?
+/// A [`Reference`] to a screeps memory object
 pub struct MemoryReference(Reference);
 
 impl AsRef<Reference> for MemoryReference {
@@ -42,46 +97,60 @@ impl MemoryReference {
         MemoryReference(reference)
     }
 
-    pub fn bool(&self, path: &str) -> bool {
-        js_unwrap!(Boolean(@{self.as_ref()}[@{path}]))
+    pub fn bool(&self, key: &str) -> bool {
+        js_unwrap!(Boolean(@{self.as_ref()}[@{key}]))
     }
 
-    pub fn num(&self, path: &str) -> Option<f64> {
+    pub fn path_bool(&self, path: &str) -> bool {
+        js_unwrap!(Boolean(_.get(@{self.as_ref()}, @{path})))
+    }
+
+    pub fn f64(&self, key: &str) -> Result<Option<f64>, ConversionError> {
         (js! {
-            return (@{self.as_ref()})[@{path}];
+            return (@{self.as_ref()})[@{key}];
         }).try_into()
-            .map(Some)
-            .unwrap_or_default()
     }
 
-    pub fn int(&self, path: &str) -> Option<i32> {
+    pub fn path_f64(&self, path: &str) -> Result<Option<f64>, ConversionError> {
         (js! {
-            return (@{self.as_ref()})[@{path}];
+            return _.get(@{self.as_ref()}, @{path});
         }).try_into()
-            .map(Some)
-            .unwrap_or_default()
     }
 
-    pub fn string(&self, path: &str) -> Option<String> {
+    pub fn i32(&self, key: &str) -> Result<Option<i32>, ConversionError> {
         (js! {
-            return (@{self.as_ref()})[@{path}];
+            return (@{self.as_ref()})[@{key}];
         }).try_into()
-            .map(Some)
-            .unwrap_or_default()
     }
 
-    pub fn dict(&self, path: &str) -> Option<MemoryReference> {
+    pub fn path_i32(&self, path: &str) -> Result<Option<i32>, ConversionError> {
         (js! {
-            var v = (@{self.as_ref()})[@{path}];
-            if (_.isArray(v)) {
-                return null;
-            } else {
-                return v || null;
-            }
+            return _.get(@{self.as_ref()}, @{path});
+        }).try_into()
+    }
+
+    pub fn string(&self, key: &str) -> Result<Option<String>, ConversionError> {
+        (js! {
+            return (@{self.as_ref()})[@{key}];
+        }).try_into()
+    }
+
+    pub fn path_string(&self, path: &str) -> Result<Option<String>, ConversionError> {
+        (js! {
+            return _.get(@{self.as_ref()}, @{path});
+        }).try_into()
+    }
+
+    pub fn dict(&self, key: &str) -> Result<Option<MemoryReference>, ConversionError> {
+        (js! {
+            return (@{self.as_ref()})[@{key}];
+        }).try_into()
+    }
+
+    pub fn path_dict(&self, path: &str) -> Result<Option<MemoryReference>, ConversionError> {
+        (js! {
+            return _.get(@{self.as_ref()}, @{path});
         }).try_into()
-            .map(Some)
-            .unwrap_or_default()
-            .map(MemoryReference)
     }
 
     /// Get a dictionary value or create it if it does not exist.
@@ -110,48 +179,57 @@ impl MemoryReference {
         js_unwrap!(Object.keys(@{self.as_ref()}))
     }
 
-    pub fn del(&self, path: &str) {
+    pub fn del(&self, key: &str) {
+        js! {
+            (@{self.as_ref()})[@{key}] = undefined;
+        }
+    }
+
+    pub fn path_del(&self, path: &str) {
         js! {
-            (@{self.as_ref()})[@{path}] = undefined;
+            _.set(@{self.as_ref()}, @{path}, undefined);
         }
     }
 
-    pub fn set<T>(&self, path: &str, value: T)
+    pub fn set<T>(&self, key: &str, value: T)
     where
         T: JsSerialize,
     {
         js! {
-            (@{self.as_ref()})[@{path}] = @{value};
+            (@{self.as_ref()})[@{key}] = @{value};
         }
     }
 
-    pub fn arr<T>(&self, path: &str) -> Option<Vec<T>>
+    pub fn path_set<T>(&self, path: &str, value: T)
     where
-        T: TryFrom<Value, Error = <Reference as TryFrom<Value>>::Error>,
+        T: JsSerialize,
     {
-        let x: Reference = (js! {
-            var v = (@{self.as_ref()})[@{path}];
-            if (!_.isArray(v)) {
-                return null;
-            } else {
-                return v || null;
-            }
-        }).try_into()
-            .ok()?;
+        js! {
+            _.set(@{self.as_ref()}, @{path}, @{value});
+        }
+    }
 
-        // Memory arrays don't have the regular Array as their prototype - they
-        // have the 'outside' type.
-        let as_arr: Array = unsafe {
-            use stdweb::ReferenceType;
-            Array::from_reference_unchecked(x)
-        };
+    pub fn arr<T>(&self, key: &str) -> Result<Option<Vec<T>>, ConversionError>
+    where
+        T: TryFrom<Value, Error = ConversionError>,
+    {
+        (js! {
+            return (@{self.as_ref()})[@{key}];
+        }).try_into()
+    }
 
-        as_arr.try_into().ok()
+    pub fn path_arr<T>(&self, path: &str) -> Result<Option<Vec<T>>, ConversionError>
+    where
+        T: TryFrom<Value, Error = ConversionError>,
+    {
+        (js! {
+            return _.get(@{self.as_ref()}, @{path});
+        }).try_into()
     }
 }
 
 impl TryFrom<Value> for MemoryReference {
-    type Error = <Reference as TryFrom<Value>>::Error;
+    type Error = ConversionError;
 
     fn try_from(v: Value) -> Result<Self, Self::Error> {
         let r: Reference = v.try_into()?; // fail early.
@@ -168,6 +246,7 @@ impl TryFrom<Value> for MemoryReference {
     }
 }
 
+/// Get a reference to the `Memory` global object
 pub fn root() -> MemoryReference {
     js_unwrap!(Memory)
 }